Biomedically-important compounds will be investigated by mass spectrometry (and GC-MS) under conditions of electron and/or chemical ionization for structurally-useful fragmentation patterns as well as for advantages of selectivity and sensitivity that can be used as the basis for developing quantitative methodology for steroids, hydroxypolyenoic acids, and other compounds. A series of hydroxy-polyunsaturated carboxylic acids will be prepared, altered chemically, derivatized, and their mass spectrometric fragmentation patterns studied to provide fundamental structural information. This microanalytical methodology will be used for the identification of previously undescribed compounds of this type during biomedical studies of the significance of lipoxygenases in the areas of malignancy, immunologic response, and pulmonary distress. Selective ionization using chemical ionization with ammonia will be used to advantage in developing quantitative methodology for certain steroids (prednisolone, dexamethasone, and 6 beta-hydroxy-cortisol) and hydroxy-polyenoic fatty acids following conversion of the allylic hydroxyl function to the x,beta-unsaturated ketone. Novel structural information from negative chemical ionization (NCI) mass spectrometry of hydroxy-polyenoic acids, steroids, and prostaglandins will be used to complement or supplement that available from conventional EI mass spectra. The technique of NCI will also be explored for advantages of sensitivity in detecting modified and/or derivatized compounds of this type. A basic study of electrophilic derivatives of these compounds will be made with the strategy that the electrophilic moiety must be well-integrated into the parent compound either with a double bond or via a cyclic structure. The objective of these studies is to obtain new information from the mass spectrometry of appropriate derivatives to develop improved, quantitative assays for specific hydroxy-polyenoic acids, steroids, and prostaglandins, and to expand the application of positive and negative chemical ionization to lipids in general.